Can anyone please help???

A billiard ball (A) with a m of 0.165 kg is travelling at 4.2 m/s. It strikes ball B, which is identical to ball A and is stationary. Ball A continues on at an angle of 25� to the left of its original direction, while ball B moves 65� to the right. Write a simplified equation, in terms of the m and velocity variables, to show how the law of conservation of momentum could be applied to this situation.